The present invention relates to devices for discouraging the entry of birds into spaces where their presence is undesirable, and more particularly, to a rotating device for scaring birds away from an area in which their presence is undesirable.
In coastal regions of the United States and other countries, marine craft, docks, aids to navigation and other marine structures suffer considerable damage and soilage from the droppings of sea gulls, terns, pelicans, cormorants and other birds. Similarly, communities near garbage dumps and land fills, which often attract large numbers of birds, may sustain similar soilage and damages, such as xe2x80x9cwhite washedxe2x80x9d rooftops.
Many devices, such as flags, plastic owls, snakes and other animals, noisemakers, deck sweepers and the like, have been tried in the past to deter birds from alighting on such structures. These prior art devices have had only limited success, at least in part because birds seem to become adapted to the presence of the device and then to ignore it.
The bird repeller of the present invention repels birds through a combination of sound, vibration and visual effects, which annoy the birds enough to prevent them from landing within 10-15 feet of the repeller. Furthermore, the almost constant variations in these effects prevent the birds from getting so use to the repeller that they come to ignore it over a period of time. Prototype testing suggests that one repeller would be effective to keep free of bird droppings an area of 300 square feet or more, and that, over an extended period of time, birds will stay as far away from the repeller as they did on the first day of installation. It is believed that birds do not get accustomed to the sound, vibration and visual effects of the device because these effects are constantly changing with the rotational speed of the rotor member, which varies with the changes in the driving wind velocity.
The bird repeller comprises a revolving hollow rotor that has laterally projecting fins adjacent to vents in a barrel section of the rotor. The fins are shaped and arranged to catch even the slightest breeze to create a wind turbine effect that spins the rotor on a vertical axis. As air currents of the wind pass across the fins and through the vents, they create a whirring sound that varies with the slightest change in the wind velocity. In addition to the whirring sound, a drum section of the rotor connects the barrel section to a neck of the rotor that rubs and vibrates against a vertical pole on which a head section of the rotor is rotatably mounted. Optionally, bells, clappers or other shakable noisemakers may be attached to an intermediate section of the pole, which also vibrates and shakes in response to the rubbing action of the rotor neck against the pole. The resulting noise and vibratory sounds also change constantly with the velocity of the wind.
In addition, the movement of the large projecting fins in the light of daytime is believed to cause a visual disturbance to the birds. This visual disturbance may be enhanced by the addition of holographic eyes or other designs on the fins, the designs being located preferably on the side of the fins in the direction of their rotation. The fin designs may also include a sparkling material capable of reflecting light in a flashing manner as the rotor rotates. The combination of the whirring and vibratory sounds with the visual effects of the spinning fins has the consequence of making birds sufficiently uneasy that they give a wide berth to the repeller.
Another advantage to the repeller of the invention is the simplicity of its construction. The rotor, which is preferably made of plastic, is mounted on a cap adhered to the top of a head portion of the vertical mounting pole and is secured to the head cap by a stainless steel screw via a nylon spacer that serves as a rotor bearing. This rotary mounting connection allows the rotor to rotate freely around the head portion of the pole. A proximate end portion of the mounting pole is held stationery by securely fastening it to any support structure, such as by clamped metal bands, bolts, or by simply slipping the base of the pole into a fishing rod holder on a boat, dock or other support structure.
By way of example, the rotor may be fashioned from a large inverted plastic juice bottle by cutting through the bottle material along three intersecting linear lines to form the three free edges of each fin and then bending the fin radially outward along the remaining proximate edge of the fin that forms a hinge by which the fin remains attached to the barrel section of the juice bottle rotor. A vent corresponding to each fin is formed when the cut-out for the fin is bent outward. The bottle from which the rotor may be made preferably has an upper tapered portion leading to the bottle neck, and this tapered portion forms an acoustic section of the rotor that enhances the vibratory sounds caused by the neck rubbing against the pole. In other words, the wall of the acoustic section resonates in response to vibrations caused by the rubbing action between the rotor neck and the pole.
The number and size of the fins and vents may vary widely, although 4 to 8 fins and vents are preferred, more preferably 6 for the rotor size described below. Although rectangular fins and vents are shown in the drawings by way of example, these elements may have other shapes and the fins and vents on the same rotor may have different sizes and shapes. A preferred rotor size is between 8 and 12 inches long and between 4 and 6 inches in diameter at the barrel so that the rotor is compact and can be easily stored in a small space, such as a storage cabinet on a boat, when it is not deployed in its active position on the mounting pole. The neck opening, which slips over the mounting pole, is preferably between about 1.25 and about 1.5 inches in diameter where the adjacent diameter of the mounting pole is about 1 inch. This gives a clearance of about 0.125 to about 0.25 inch between the neck and opposite sides of the mounting pole, which provides a preferred frequency of bird repelling vibrations. Where the overall length of the rotor is about 12 inches, the preferred lengths of the head, barrel, acoustic section and neck are respectively about 0.5 inch, about 6.5 inches, about 3.75 inches and about 1.25 inches. For a barrel of about 6.5 inches long and about 5.0 inches in diameter, the fins and vents are preferably about 2.75 inches long and about 1.75 inches wide, and the optimum number of fins and vents is 6.
Although the preferred material of the rotor is plastic, other materials may be used, such as steel, aluminum and other metals. Instead of nylon, the bearing washer may be made of Teflon(copyright) or stainless steel. The mounting pole may be made of hollow or solid plastic, wood or metal. The plastic may be PVC, the wood may be pine or oak, and the metal may be steel or aluminum.
The need for a bearing washer may be avoided by the rotary mounting structure employed in a second embodiment of the invention. In this embodiment, a lag-bolt type structure passes through and is secured to the head section of the rotor, with the shaft of the bolt projecting into the rotor along its rotational axis. The distal end of the bolt shaft rests freely in and rotates within a socket formed by a small metal or plastic cup that is mounted on the cap secured to the head of the vertical mounting pole. This second embodiment of the invention may have greater rotational wobble than the first embodiment, and thereby may produce a more effective vibratory sound by the rubbing action between the neck of the rotor and the mounting pole. The rotary connection may also have a longer wear life than the mounting screw and washer bearing of the first embodiment. However, the first embodiment may be mounted either upright, as shown in the drawings, or upside down with the proximate end of the mounting pole secured to an overhead mounting structure, whereas the second embodiment can only be mounted in an upright position.
The above features and benefits and the proven effectiveness of a prototype, combined with simplicity and low cost, make the bird repeller of the present invention significantly superior to any previously known repeller of the prior art.